Field of the Invention
The present invention relates primarily to the configuration of a sonic speed measurement device that uses ultrasonic waves to measure the sonic speed through a measurement object.
Background Information
There is a known sonic speed measurement device that transmits an ultrasonic wave signal to a measurement object, receives the ultrasonic wave signal that comes back from the measurement object, and derives the sonic speed through the measurement object based on the received ultrasonic wave signal. This type of sonic speed measurement device is discussed in Japanese Laid-Open Patent Application Publication No. 2010-246692 (Patent Literature 1), for example.
The sonic speed measurement device discussed in Patent Literature 1 comprises a plurality of wave receivers. Patent Literature 1 discloses a configuration in which the sonic speed through a measurement object is postulated, the propagation time until ultrasonic waves reach the receivers is calculated based on a postulated sonic speed value, and received signals received by the receivers are shifted by an amount of time corresponding to the propagation time to find an integrated waveform in which the shifted signals have been integrated. In Patent Literature 1, if the postulated sonic speed value is correct, the peaks of the shifted signals reinforce each other, so whether or not the postulated sonic speed value is correct can be determined by examining the integrated waveform. Also, in Patent Literature 1, since the peaks of the received signals received by the receivers do not have to be detected precisely, noise is less likely to have an effect.